Oil cooler

ABSTRACT

An oil cooler includes a pair of spaced inlet/outlet boss portions; an inlet pipe and an outlet pipe coupled to the inlet/outlet boss portions, respectively; and tubes coupled to the inlet/outlet boss portions through both ends thereof to form an oil flow passage. The tubes are disposed in parallel and in a multi-stage arrangement. Each tube has a portion in fluid flow relationship with the neighboring tube at an area between the inlet and outlet pipes so oil can flow between them.

RELATED APPLICATIONS

The present application is based on, and claims priority from, KR Application Number 10-2007-0116336, filed Nov. 14, 2007, KR Application Number 10-2008-0004753, filed Jan. 16, 2008, and KR Application Number 10-2008-0109521, filed Nov. 5, 2008, the disclosures of which are hereby incorporated by reference herein in their entireties.

TECHNICAL FIELD

The present invention relates to an oil cooler, and more particularly, to an oil cooler provided with communicating portions formed therein to allow oil flowed therein to be uniformly distributed and capable of promoting a generation of turbulent flow of oil to enhance a heat-exchanging performance of oil and cooling water.

BACKGROUND ART

A radiator is a device for preventing a temperature of an engine from being increased above a predetermined value. The radiator is a heat exchanging device for circulating cooling water in the engine to absorb heat generated by combustion in the engine and radiating the heat contained in high-temperature cooling water to an outside while the high-temperature cooling water is circulated and passes through the radiator by a water pump, thereby preventing an over-heating of the engine and maintaining an optimum driving state.

In the meantime, an oil cooler is provided in an automatic transmission vehicle for cooling engine oil in a torque converter or a power transmission system. Since a temperature of the oil in the automatic transmission communicated with the oil cooler is higher than that of the radiator, the oil is heat-exchanged by utilizing engine cooling water in the radiator, and so oil is cooled.

The oil cooler may be classified mainly into an internal-type oil cooler provided in a radiator tank and an external-type oil cooler. Also, the internal-type oil cooler may be classified into a dual tubular-type oil cooler having a dual tubular shape and a stack-type oil cooler. The dual tubular-type oil cooler and a radiator tank assembly are illustrated in FIG. 1A. The dual tubular-type oil cooler 10 shown in FIG. 1A is provided in a tank of the radiator, a concentric main body 11 is provided, and an inlet pipe 13 and an outlet pipe 14 are formed on one side of the main body 11 to allow oil to be introduced into the main body and to be discharged out of the main body 11. Cooling water of the radiator is flowed in the main body 11 and flowed out of the main body 11 to cool oil supplied to the main body 11.

In order to enhance the heat exchanging efficiency, a plurality of channels is formed in the main body 11 by an inner fin and the like in the longitudinal direction of the tank.

However, there is a problem that, in a case where a length of the oil cooler is limited, since the internal-type oil cooler has the dual tubular shape, a capacity of the oil cooler is limited, and since the structure for distributing oil to the channels formed on the main body is complicated, the productivity is lowered.

The stack-type oil cooler is shown in FIG. 1B, the stack-type oil cooler 20 comprises a pair of header tanks 25 spaced from each other at a predetermined distance like a construction of conventional heat exchanger; an inlet pipe 23 and an outlet 24 formed on the header tanks 25, respectively; tubes 21 fixed by the header tanks 25 through both ends thereof to form flow passages; and fins 22 disposed between the tubes 21.

The fin 22 in the stack-type oil cooler means an outer fin disposed between the tubes 21 and formed at a portion in the radiator tank through which cooling water is flowed, and inner fins are formed additionally in a space through which oil in the tube is flowed.

The above stack-type oil cooler has the advantage that the tubes and the fins are provided in a stack state to enhance the heat exchanging efficiency, but has the drawback that a manufacturing cost is relatively high.

Also, although a portion on which the outer fin is formed functions to increase an area which is heat-exchanged with cooling water (which is liquid flowed in the radiator tank), there is a problem that the portion on which the outer fin is formed obstructs a flow of cooling water.

In addition, oil flowed in the dual tubular-type oil cooler and the stack-type oil cooler has a high viscosity so that, as compared with conventional fluid, a flow of oil is not flowed smoothly. Consequently, the dual tubular-type oil cooler and the stack-type oil cooler have the problem that it is difficult to distribute uniformly oil introduced through an inlet pipe so that the heat exchanging efficiency is lowered.

A flow resistance and flow characteristic of oil flowed in the oil cooler, and a density of fins provided in the oil cooler influence considerably a performance of the oil cooler.

FIG. 2 is a perspective view of an inner fin 12 or 22 provided in the conventional oil cooler. As indicated by an arrow of A, in a case where oil is flowed in the direction perpendicular to partition portions 30 of the inner fin 12 or 22, oil is dispersed by the partition portions 30 in all directions so that a flow of oil is transformed in to a turbulent flow. However, the above structure increases the oil resistance in proportion to a turbulent flow, so oil is not flowed smoothly. In order to solve the above problem, a density of the inner fin 12 or 22 should be reduced, and as a result, a heat radiating area is reduced to deteriorate an overall heat radiating performance of the oil cooler.

In order to solve the above problem, the structure in which the partition portions 30 of the inner fin 12 or 22 are perpendicular to the flow direction of oil indicated as an arrow B in FIG. 2 has been proposed.

The structure of the inner fin shown in FIG. 2 has the advantage that an oil resistance is lowered and a density of the inner fin is increased to enable a heat radiating performance to be enhanced. In the oil cooler comprising the inner fin having the above structure, however, a flow of oil is similar to a streamline flow, and so a heat exchanging performance is deteriorated due to a reduction of oil resistance.

In other words, the oil cooler being capable of guiding a flow of oil to the B direction shown in FIG. 2 to lower oil resistance and promoting a generation of turbulent flow of oil to enhance the heat-radiating performance has been required.

DISCLOSURE OF THE INVENTION

The present invention is conceived to solve the above-mentioned problem, it is an object of the present invention to provide an oil cooler comprising a communicating portion capable of mixing oil and formed between tubes to make a distribution of oil uniform.

Another object of the present invention is to provide an oil cooler which can transform a flow of oil into a turbulent flow to allow oil to be flowed smoothly, thereby enhancing a heat exchanging efficiency.

An oil cooler according to the present invention comprises a pair of inlet/outlet boss portions 110 spaced from each other at a predetermined distance; an inlet pipe 120 and an outlet pipe 130 coupled to the inlet/outlet boss portions 110, respectively; and tubes 140 fixed by the inlet/outlet boss portions 110 through both ends thereof to form an oil flow passage. Here, wherein the tube 140 is formed with a communicating portion 160 for communicating the tube 140 with the neighboring tube 140 at an area between the inlet pipe 120 and the outlet pipe 130 to allow oil to be flowed therebetween.

In addition, the plurality of communicating portions 160 are formed in the longitudinal direction of the tube 140, and the communicating portions 160 are formed on one line in the stacking direction of the tubes 140.

The communicating portions 160 are formed on an area of all the tubes 140 in the direction perpendicular to a flow direction of oil in the tube 140 to allow oil flowed in the specific tube 140 to be flowed into all other tubes 140 through the communicating portions 160. At this time, the flow direction of oil flowed upstream of the communicating portion 160 is the same as that of oil flowed downstream of the communicating portion 160 in the tubes 140.

In addition, the tube 140 is formed by coupling an upper plate 141 to a lower plate 142, one of two neighboring tubes 140 has a first protrusion portion 143 formed on the plate 142 thereof and protruded perpendicularly toward the other tube 140, the other tube has a second protrusion portion 144 formed on the plate 141 thereof, protruded perpendicularly toward one tube 140 and being closely contacted with an inner surface or an outer surface of the first protrusion portion 143, and the communicating portion 160 is formed by coupling the first protrusion portion 143 to the second protrusion portion 144.

The oil cooler is characterized in that the tube 140 has an hollow portion 145 formed by cutting out some area thereof, the hollow portions 145 of the tubes 140 correspond to each other in the stacking direction of the tubes 140 and a communicating member 161 connecting the hollow portions 145 of the neighboring tubes 140 to each other is formed to form the communicating portion 160.

Also, the tube 140 comprises an inner fin 150 provided therein, and the inner fin 150 has an fin-free portion 155 by cutting out some area thereof and formed at a place corresponding to the communicating portion 160 to allow oil flowed in the communicating portion 160 to be flowed smoothly.

Here, the inner fin 150 comprises first rows and second rows disposed alternately and repeatedly, wherein the second row has the same configuration as the first row and is spaced apart from a reference of the first partition portions 152 of the first rows at a predetermined distance, the first row comprises a plurality of first partition portions 152 protruded perpendicularly and upwardly from a plane portion 151, extending portions 153 extended perpendicularly from the first partition portions 152 and paralleled with the plane portions 151 and second partition portions 154 extended perpendicularly and downwardly from the extending portion 153 and paralleled with the first partition portions 152, wherein the first partition portions 152, the extending portions 153 and the second partition portions 154 are disposed repeatedly in the first row.

Also, the inner fin 150 is disposed such that the first partition portion 152 and the second partition portion 154 are parallel with a flow direction of oil flowed in the oil cooler.

In the meantime, an oil cooler according to the present invention comprises a pair of inlet pipe 120 and outlet pipe 130 spaced from each other at a predetermined distance; the tubes 140 connected to the inlet pipe 120 and outlet pipe 130 through both ends thereof to form an oil flow passage; and turbulence generating parts formed on the oil flow passage in the tubes 140.

Here, the turbulence generating part is a communicating portion 160 through which the neighboring tubes 140 are communicated with each other for allowing oil to be flowed between the tubes 140.

In addition, the communicating portions 160 are formed on an area of all the tubes 140 in the direction perpendicular to a flow direction of oil in the tube 140 to allow oil flowed in the specific tube 140 to be flowed into all other tubes 140 through the communicating portions 160.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a sectional view illustrating a conventional dual tubular shaped coil cooler and a radiator tank assembly;

FIG. 1B is a perspective view showing a conventional stack-type oil cooler;

FIG. 2 is a perspective view of an inner fin provided in a conventional oil cooler;

FIG. 3 is a perspective view showing an oil cooler according to one embodiment of the present invention;

FIG. 4A is a partial sectional perspective view of an oil cooler of the present invention;

FIG. 4B is a perspective view of an inner fin shown in FIG. 4A;

FIG. 5A is a partial sectional view showing an oil cooler of the present invention;

FIG. 5B is a schematic view showing temperatures of points C and D shown in FIG. 5A;

FIG. 6 is a perspective view showing a tube of an oil cooler according to another embodiment of the present invention;

FIG. 7 is a view illustrating a process for manufacturing a tube constituting an oil cooler of the present invention;

FIG. 8 is a view illustrating another process for manufacturing a tube and a communicating portion constituting an oil cooler of the present invention;

FIG. 9 is another partial sectional perspective view of an oil cooler of the present invention;

FIG. 10 is an exploded perspective view of a tube constituting an oil cooler shown in FIG. 9;

FIG. 11 is a sectional view of an oil cooler according to one embodiment of the present invention;

FIG. 12 is a view showing a temperature distribution of oil in an oil cooler shown in FIG. 11;

FIG. 13 is a graph showing an average temperature of oil inside of a tube of an oil cooler shown in FIG. 11;

FIG. 14 is a graph showing an average temperature of a surface of a tube of an oil cooler shown in FIG. 11;

FIG. 15 is a graph showing a heat flow rate on a surface of a tube of an oil cooler shown in FIG. 11;

FIG. 16A is another graph showing a temperature distribution of an oil cooler shown in FIG. 11; and

FIG. 16B is a graph showing a temperature distribution of Comparison example.

DETAILED DESCRIPTION OF MAIN ELEMENTS

100: oil cooler of the present invention 110: inlet/outlet boss portion 120: inlet pipe 130: outlet pipe 140: tube 141: upper plate 142: lower plate 143: first protrusion 144: second protrusion 150: inner fin 151: plane portion 152: first partition portion 153: extending portion 154: second partition portion 155: fin-free portion 160: communicating portion

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the oil cooler 100 having the above structure according to the present invention will be explained in more detail with reference to the accompanying drawings.

FIG. 3 is a perspective view showing an oil cooler of the present invention. As shown in FIG. 3, an oil cooler 100 of the present invention comprises a pair of inlet/outlet boss portions 110 spaced apart from each other at a predetermined distance, an inlet pipe 120 and an outlet pipe 130 coupled to the inlet/outlet boss portions 110, respectively, and tubes 140 fixed by the inlet/outlet boss portions 110 through both ends thereof to form an oil flow passage. The above oil cooler 100 is characterized in that the tubes 140 are disposed in parallel and in a multi-stage and the tube 140 is formed with a communicating portion 160 for communicating the tube 140 with the neighboring tube 140 at an area between the inlet pipe 120 and the outlet pipe 130 to allow oil to be flowed therebetween.

In other words, the communicating portion 160 is formed at a region between the inlet pipe 120 and the outlet pipe 130 in a longitudinal direction of the tube 140 to allow oil introduced into the tube 140 via the inlet pipe 120 to be flowed into the neighboring tube 140 when the oil is flowed to the outlet pipe, and so a generation of turbulent flow of oil is promoted.

More concretely, as compared with the conventional oil cooler in which oil introduced through the inlet pipe 120 and one inlet/outlet boss portion 110 is flowed along the specific tube 140 and then flowed through the other inlet/outlet boss 110 and the outlet pipe 130, the oil cooler 100 of the present invention has an advantage that the communicating portion 160 allows the neighboring tubes 140 to be communicated with each other to enable oil introduced into the specific tube 140 to be flowed into all other tubes 140 through the communicating portions 160 so that, in a case where the oil flow rate within the specific tube 140 is excessive, the flow rate in the specific tube 140 is dispersed into other tubes 140 to equalize the flow rate distributions within all the tubes 140.

In general, due to an extremely high viscosity, oil is not flowed smoothly. However, the present invention has the advantage that the communicating portions 160 cause a turbulent flow of oil to allow oil to be flowed smoothly in the oil cooler 100.

At this time, the communicating portion 160 only guides oil into other tubes 140, a flow direction of oil flowed upstream of the communicating portion 160 is the same as that of oil flowed downstream of the communicating portion 160.

In addition, the conventional oil cooler has the problems that, in a case where an outer fin is not provided between the tube 140 and the tube 140, since the tubes 140 are extended in the longitudinal direction and a plurality of tubes 140 are stacked, if an external force is exerted, the tube 140 is easily transformed. However, the oil cooler 100 of the present invention has the effect that the communicating portion 160 can support an outside of the tube 140 to improve the overall durability.

The communicating portion 160 may be formed by various methods. A hollow area is formed by cutting out some area of the tube 140 and an additional communicating member 161 is then coupled to the hollow area to allow the hollow area to be communicated with the additional communicating member 161, and the communicating portion may be formed by using plates 141 and 142 forming the tube 140.

FIG. 4A is a partial sectional perspective view of the oil cooler 100 of the present invention, FIG. 4B is a perspective view of an inner fin 150 shown in FIG. 4A and FIG. 5A is a partial sectional view showing the oil cooler 100 of the present invention. FIG. 4A and FIG. 5A illustrate an example in which the communicating portions 160 are simultaneously formed by using the plates 141 and 142.

In FIG. 5A, in order to illustrate a flow of oil, a configuration of the inner fin 150 provided in the tube 140 is omitted in FIG. 5A.

In the oil cooler 100 of the present invention, as shown in FIG. 4A and FIG. 5A, the tube 140 is formed by coupling the upper plate 141 to the lower plate 142. In each of the two neighboring tubes 140, a first protrusion portion 143 is formed on the plate 141 or 142 of one tube and protruded perpendicularly toward the other tube 140, a second protrusion portion 144 is formed on the plate 141 or 142 of the other tube 140 and protruded perpendicularly toward one tube 140. At this, time, the second protrusion is closely contacted with an inner surface or an outer surface of the first protrusion portion 143, and the communicating portion 160 is formed by coupling the first protrusion portion 143 to the second protrusion portion 144.

In other words, the first protrusion portion 143 is formed protrudely and perpendicularly on the lower plate constituting one tube 140 and the second protrusion portion 144 is formed protrudely and perpendicularly on the upper plate 141 constituting the other tube 140 to communicate the neighboring one tube 140 and the other tube 140 with each other. The first protrusion portion 143 and the second protrusion portion 144 have the hollow configurations, so the tube 140 and tube 140 are communicated with each other by a coupling of the first protrusion portion 143 and the second protrusion portion 144.

A coupling of the first protrusion portion 143 and the second protrusion portion 144 can be achieved by the welding method which is the same as that performed for coupling the upper plate 141 and the lower plate 142 constituting the tube 140, and coupling surfaces of two protrusion portions are not exposed to an outside so that corrosion problems of the coupling surface caused by a reaction between the coupling surface and cooling water of the radiator flowed an outside of the tube can be prevented in advance.

Although FIG. 4A to FIG. 5A show that the first protrusion portion 143 is formed on the lower plate 142 on one tube 140 and the second protrusion portion 144, which is in contact with an outer surface of the first protrusion portion 143, is formed on the other tube 140, the present invention is not limited thereto, but can be modified variously.

Due to the communicating portion 160 formed as described above, as shown in FIG. 5A, a flow of oil flowed through the tube 140 is transformed into a turbulent flow so that oil can be flowed easily into another tube 140, and the oil cooler 100 of the present invention has an advantage that since oil is flowed smoothly, the heat exchange efficiency can be more increased.

In addition, FIG. 3 and FIG. 4A show an example of the oil cooler 100 in which the communicating portions 160 are formed at two places of the tube 140 in the longitudinal direction and formed through the overall area of the tubes 140. Here, the communicating portion 160 is perpendicular to a flow direction of oil in the tube 140. Depending on a capacity of the oil cooler 100, a dimension of the tube 140 and the like, a plurality of communicating portion 160 can be formed in a longitudinal direction of the tube 140. The communicating portions 160 can be perpendicular to a flow direction of oil in the tube 140 (in the direction which is paralleled with a direction of the inlet pipe 120 or the outlet pipe 140) and can be formed through the overall area of the tubes 140 or allow only some tubes 140 to be communicated with each other.

In the oil cooler 100 of the present invention, in a case where a plurality of communicating portions 160 are formed, it is preferable that a plurality of communicating portions 160 are formed on the same line along a stacking line of the tubes 140 to enable oil flowed in one tube 140 to be flowed smoothly into all other tubes 140.

In the meantime, the oil cooler 100 of the present invention comprises the inner fin 150 provided in the tube 140 for transforming a flow of oil into the turbulent flow to increase the heat exchange efficiency. As shown in FIG. 4B, the inner fin 150 comprises first rows and second rows disposed alternatively. In each of the first rows, a first partition portion 152 protruded perpendicularly and upwardly from a plane portion 151, an extending portion 153 extended perpendicularly from the first partition portion 152 and paralleled with the plane portion 151, and a second partition portion 154 extended perpendicularly and downwardly from the extending portion 153 and paralleled with the first partition portion 152 are disposed repeatedly. Also, each of the second rows has a configuration which is the same as that of the first row except that a reference location of the first partition portion 152 in the second row is spaced from a reference location of the first partition portion 152 in the first row at predetermined distance. At this time, it is preferable that oil flowed in the oil cooler 100 is flowed in the direction which is parallel with the first partition portion 152 and the second partition 154 to reduce a resistance exerted to oil and increase a density of the fin, and so a heat-radiating performance is improved and a generation of turbulent flow of oil can be promoted by the communicating portions 160 to optimize the heat exchange performance.

In the oil cooler 100 of the present invention, an outer fin can be provided between the tube 140 and the tube 140 to allow oil to be heat-exchanged with cooling water flowed in the radiator tank. On the contrary, by not providing the outer fin, it is possible to increase the number of stages of the tubes 140 provided in a limited space.

In a case where the outer fin is not provided, it is possible to increase a flow rate of cooling water which is heat-exchanged with oil flowed in the tube 140 and although a dimension of the radiator tank becomes small, the number of the stages of the tubes 140 can be increased to improve the heat exchange performance.

FIG. 5B is a schematic view showing temperatures of points C and D shown in FIG. 5A. More concretely, (a) of FIG. 5B is a schematic view showing a variation of temperature according to a height of the point C (a perpendicular direction of a central line of the uppermost tube) shown in FIG. 5A, and (b) of FIG. 5B is a schematic view showing a variation of temperature according to a height of the point D shown in FIG. 5A.

As shown in FIG. 5B, before oil is reached the communicating portion 160, oil is flowed in a streamline flow state in which a temperature of oil is increased toward an inside of the tube 140, and the temperature difference between an inside and an outer surface of the tube 140 is large. However, after oil passes the communicating portion 160, a temperature difference between an inside and outside of the tube 140 becomes small so that a temperature of an inside of the tube 140 becomes more uniform (see FIG. 12)

FIG. 6 is a perspective view showing a tube 140 of the oil cooler 100 according to another embodiment of the present invention. As one example of the tube, FIG. 3 to FIG. 5A illustrate the tube 140 having the communicating portion 160 with a rectangular section. As shown in FIG. 7, it will be apparent that the communicating 160 has a circular section. In addition, a shape of the communicating portion 160 is not limited to the rectangular section and the circular section if the communicating portion 160 connects outsides of the tubes 140 to enable oil flowed in the tube 140 to be flowed into another tube 140.

FIG. 7 is a view illustrating a process for manufacturing the tube 140 constituting the oil cooler 100 of the present invention, a process for manufacturing the tube 140 of the oil cooler 100 as illustrated in FIG. 4A, FIG. 4B and FIG. 5A will be described. As shown in (a) of FIG. 7, the upper plate 141 and the lower plate 142 constituting the tube 140 are prepared, and both sides of the upper plate 141 and the lower plate 142 are bent to enable the upper plate 141 and the lower plate 142 to be bonded to each other as shown in (b) of FIG. 7. As shown (c) of FIG. 7, the first protrusion 143 and the second protrusion 144 are formed on the upper and lower plates 141 and 142, and the upper plate 141 and the lower plate 142 are bonded to each other to form the tube 140 having the inner pin 150 provided therein and the communicating portion 160.

FIG. 8 is a view illustrating another process for manufacturing the tube 140 and the communicating portion constituting the oil cooler 100 of the present invention. Besides the plates 141 and 142 shown in FIG. 7, extruding type tubes 140 shown in (a) of FIG. 8 may be employed in the oil cooler 100 of the present invention. As shown in (b) of FIG. 8, at this time, each of the extruding type tubes 140 has an hollow portion 145 formed by cutting out some area thereof, the hollow portions 145 of the tubes 140 correspond to each other in the stacking direction of the tubes 140.

Next, as shown in (c) of FIG. 8, a hollow tubular communicating member 161 provided forming a communicating portion 160 and having a height corresponding to a distance between the tubes 140 can be fixed by the hollow portions of the tubes 140 to form the communicating portion 160. Besides the shapes shown in FIG. 7 and FIG. 8, if the communicating portion 160 connects the neighboring tubes to allow oil to be flowed in the tubes 140, the communicating of the oil cooler 100 of the present invention can be modified variously.

FIG. 8 shows an example of the communicating portion-forming communicating member 161 having protrusions formed on upper and lower circumference surfaces for enabling a depth of the communicating member 161 to be inserted into the hollow portion 145 of the tube 140 to be adjusted.

FIG. 9 is another partial sectional perspective view of the oil cooler 100 of the present invention, and FIG. 10 is an exploded perspective view of the tube 140 constituting the oil cooler 100 shown in FIG. 9. The oil cooler 100 shown in FIG. 9 has a basic structure which is the same as that of the oil cooler 100 shown in FIG. 4A. However, the an inner fin 150 is provided in the tube 140, and a fin-free portion 155 may be formed on a location of the inner fin 150 corresponding to the communicating portion 160 for allowing oil flowed in the communicating portion 160 to be flowed smoothly.

The term “fin-free portion 155” means an empty space of the inner fin 150 corresponding to the communicating portion 160. Although the rectangular-shaped fin-free portion 155 is shown in FIG. 9, the shape of fin-free portion 155 may be formed variously according to an element such as a shape of the communicating portion 160.

The plane portions 151 and the extending portions 153 of the inner fin 150 are formed in the direction perpendicular to a flow direction of oil flowed in the communicating portion 160 so that the plane portions 151 and the extending portions 153 may act as the factors interrupting a flow of oil. In the oil cooler 100 of the invention, accordingly, the fin-free portion 155 is formed by cutting out some area thereof of the inner fin 150 corresponding to the communicating portion 160 to allow oil to be flowed smoothly between the tubes 140. As a result, it is possible to maximize a function of the communicating portion 160 provided for transforming a flow of oil into a turbulent flow to increase the heat-exchanging efficiency.

EMBODIMENT 1

The oil cooler 100 shown in FIG. 11 was utilized in embodiment 1, the detail dimension of the oil cooler 1000 used in embodiment 1 were as follows: a distance between a central line of the inlet pipe 120 and a central line of the outlet pipe 130 was 375 mm, a distance between one inlet/outlet boss portion 110 and the other inlet/outlet boss portion 110 (except a portion of the tube 140 to be inserted into the inlet/outlet boss portion 110; hereinafter, referred to as “a length of the tube 140”, a x-axial direction in FIG. 3) was 346 mm, a width of the tube 140 (a y-axial direction in FIG. 3) was 26 mm, the tubes 140 were stacked in seven stages, and the communicating portions 160 with a circular section were formed at two places, a central line of the communicating portion 160 being spaced from the inlet/outlet boss 110 by 84 mm.

At this time, except the communicating portions 160, all elements of the oil cooler 1000 used as Comparison example are the same as those of the oil cooler used as embodiment 1. Under the conditions that a flow rate of oil introduced via the inlet pipe 120 was 12 l/min., a temperature was 414 K, a flow rate of radiator cooling water flowed on an outer surface of the oil cooler 100 was 80 l/min and a water temperature was 383 K, experiments for embodiment 1 and Comparison example were conducted.

FIG. 12 is a view showing a temperature distribution of oil in the oil cooler 1000 shown in FIG. 11. In actual, in the temperature distribution of oil in the tube 140 before the oil passed the communicating portion 160, a temperature in an inside of one tube 140 was high, a temperature of a surface of the tube was low. Also, it was possible to verify that a temperature distribution of an inside of the tube 140 become uniform after the oil passed the communicating portion 160.

FIG. 13 is a graph showing an average temperature of oil inside of the tube 140 of the oil cooler 100 shown in FIG. 11, FIG. 14 is a graph showing an average temperature of a surface of the tube 140 of the oil cooler 100 shown in FIG. 11, and FIG. 15 is a graph showing a heat flow rate (a flow ratio of heat transmitted to cooling water out of the plates 141 and 142 per the unit area of the plates 141 and 142) on a surface of the tube 100 of the oil cooler 100 shown in FIG. 11. Here, the reference point is an outermost portion of the inlet/outlet boss portion 110 at which the inlet pipe 120 is provided, and the temperature values at the points along the overall length of the tube 140 on are shown in FIG. 13 and FIG. 14.

In the above drawings, an upward/downward dotted line indicates a central line of the communicating port 160, a thick solid line represents embodiment 1 of the present invention, and a thin dotted line represents Comparison example.

As shown in FIG. 13, on the whole, as compared with Comparison example, the average temperature of oil in the tube 140 of embodiment 1 of the present invention was lowered and the average temperature of oil passing the first communicating portion 160 and the second communicating portion 160 was rapidly lowered, and so it was possible to verify that, as compared with Comparison example, the heat exchange efficiency of embodiment 1 was enhanced.

FIG. 14 is a graph showing an average temperature of a surface of the tube 140. FIG. 14 shows that Embodiment 1 of the present invention utilizing the communicating portions 160 solved the ununiformity (a high temperature difference between an inside and a surface) of temperature in the tube 140 so that a heat exchange for oil flowed in the tube 140 could be performed more actively. In addition, with the passage of time, oil flowed in the tube 140 was mixed with oil on a surface of tube 140 and oil was heat-exchanged with external cooling water, so an average temperature of a surface of the tube 140 was lowered to a value which is similar to that of Comparison example. Also, when the oil passed the second communicating portion 160, the effect (which falls short of the effect obtained when the oil passed the first communicating portion 160) was apparently obtained.

FIG. 15 is a graph showing an average heat flow rate on a surface of the tube 140 of the oil cooler 100 shown in FIG. 11. The term “heat flow rate” represents a flow ratio of heat transmitted to external cooling water per the unit area of a surface of the tube 140, and the graph in FIG. 15 has a curve similar to that of the graph in FIG. 14.

Accordingly, as compared with Comparison example on which the communicating portion 160 was not formed, in embodiment 1 of the present invention, the temperature contribution in the tube 140 become uniform with the communicating portion 160 as the center so that oil in the tube 140, which was not heat-exchanged properly, could be heat-exchanged with external cooling water to enhance the heat-exchanging performance of the oil cooler.

In addition, it was possible to verify that, in embodiment 1 of the present invention, the ununiformity of temperature distribution in the specific tube 140 was solved and oil flowed in the specific tube 140 could be flowed into another tube 140 so that oil flowed in the tube 140, which was placed at a mid position (in the heightwise direction) at which it was difficult to heat-exchange, was mixed to transform entirely a flow of oil into the turbulent flow, thereby enhancing the heat-exchanging efficiency.

Practically, the area marked by oblique lines in FIG. 15 means the amount of heat which was more radiated with respect to a length (mm) of the tube 140 than Comparison example.

FIG. 16A is another graph showing a temperature distribution of the oil cooler 100 shown in FIG. 11 and FIG. 16B is a graph showing a temperature distribution of Comparison example. The above drawings show the temperature distributions on the inlet/outlet boss portion 110 at which the inlet pipe 120 was provided and a portion of the tube 140 corresponding to a central portion of the oil cooler 100.

As compared with Comparison example of FIG. 16B, it was possible to verify that a temperature was extremely raised with the region (on which the communicating portion is formed) as the center in embodiment 1 of FIG. 16A,

As a result, since the amount of radiated heat was proportion to a temperature difference, if the temperature of oil was raised, a difference between cooling water and oil was increased to increase the amount of radiated heat and the overall average temperature of oil was further lowered.

As shown in FIG. 13 to FIG. 16B, as compared with Comparison example, in embodiment 1 of the present invention in which two communicating portions 160 were formed, a flow of oil was transformed into the stronger turbulent flow so that a heat exchange was performed more actively. Consequently, a temperature of oil flowed in the oil cooler 100 could be lowered effectively.

In the meantime, another oil cooler 100 according to the present invention comprises a pair of inlet pipe 120 and outlet pipe 130 spaced from each other at a predetermined distance; the tubes 140 connected to the inlet pipe 120 and outlet pipe 130 through both ends thereof to form an oil flow passage; and turbulence generating parts formed on the oil flow passage in the tubes 140. At this time, the turbulence generating part is the communicating portion 160 through which the neighboring tubes 140 are communicated with each other for allowing oil to be flowed between the tubes 140.

In addition, the communicating portions 160 are formed on areas of all the tubes 140 and in the direction perpendicular to the flow direction of oil in the tube 140, so oil flowed in the specific tube 140 can be flowed into all other tubes 140 through the communicating portions 160. Consequently, a flow of oil flowed in the tubes 140 is transformed effectively into the turbulent flow through the communicating portions 160.

Therefore, the oil cooler of the present invention has the advantage that the communicating portion through which oil is flowed between the tubes is formed by forming the first protrusion and the second protrusion on the tubes to promote a generation of turbulent flow of oil through the communicating portion so that the heat exchanging efficiency can be enhanced.

Those skilled in the art will appreciate that the conceptions and specific embodiments disclosed in the foregoing description may be readily utilized as a basis for modifying or designing other embodiments for carrying out the same purposes of the present invention. Those skilled in the art will also appreciate that such equivalent embodiments do not depart from the spirit and scope of the invention as set forth in the appended claims. 

1. An oil cooler, comprising, a pair of inlet/outlet boss portions spaced from each other at a predetermined distance; an inlet pipe and an outlet pipe coupled to the inlet/outlet boss portions, respectively; and tubes fixed by the inlet/outlet boss portions through both ends thereof to form an oil flow passage, wherein the tubes are disposed in parallel and in a multi-stage and the tube is formed with a communicating portion for communicating the tube with the neighboring tube at an area between the inlet pipe and the outlet pipe to allow oil to be flowed therebetween.
 2. The oil cooler as set forth in claim 1, wherein the plurality of communicating portions are formed in the longitudinal direction of the tube.
 3. The oil cooler as set forth in claim 2, wherein the communicating portions are formed on one line in the stacking direction of the tubes.
 4. The oil cooler as set forth in claim 1, wherein the communicating portions are formed on an area of all the tubes in the direction perpendicular to a flow direction of oil in the tube to allow oil flowed in the specific tube to be flowed into all other tubes through the communicating portions.
 5. The oil cooler as set forth in claim 4, wherein the flow direction of oil flowed upstream of the communicating portion is the same as that of oil flowed downstream of the communicating portion in the tubes.
 6. The oil cooler as set forth in claim 4, wherein the tube is formed by coupling an upper plate to a lower plate, one of two neighboring tubes has a first protrusion portion formed on the plate thereof and protruded perpendicularly toward the other tube, the other tube has a second protrusion portion formed on the plate thereof, protruded perpendicularly toward one tube and being closely contacted with an inner surface or an outer surface of the first protrusion portion, and the communicating portion is formed by coupling the first protrusion portion to the second protrusion portion.
 7. The oil cooler as set forth in claim 4, wherein the tube has an hollow portion formed by cutting out some area thereof, the hollow portions of the tubes correspond to each other in the stacking direction of the tubes and a communicating member connecting the hollow portions of the neighboring tubes to each other is formed to form the communicating portion.
 8. The oil cooler as set forth in claim 1, wherein the tube comprises an inner fin provided therein.
 9. The oil cooler as set forth in claim 8, wherein the inner fin has an fin-free portion formed by cutting out some area thereof and formed at a place corresponding to the communicating portion to allow oil flowed in the communicating portion to be flowed smoothly.
 10. The oil cooler as set forth in claim 8, the inner fin comprises first rows and second rows disposed alternately and repeatedly, wherein the second row has the same configuration as the first row and is spaced apart from a reference of the first partition portions of the first rows at a predetermined distance, the first row comprises a plurality of first partition portions protruded perpendicularly and upwardly from a plane portion, extending portions extended perpendicularly from the first partition portions and paralleled with the plane portions and second partition portions extended perpendicularly and downwardly from the extending portion and paralleled with the first partition portions, wherein the first partition portions, the extending portions and the second partition portions are disposed repeatedly in the first row.
 11. The oil cooler as set forth in claim 10, wherein the inner fin is disposed such that the first partition portion and the second partition portion are parallel with a flow direction of oil flowed in the oil cooler.
 12. An oil cooler, comprising a pair of inlet pipe and outlet pipe spaced from each other at a predetermined distance; the tubes connected to the inlet pipe and outlet pipe through both ends thereof to form an oil flow passage; and turbulence generating parts formed on the oil flow passage in the tubes.
 13. The oil cooler as set forth in claim 12, wherein the turbulence generating part is a communicating portion through which the neighboring tubes are communicated with each other for allowing oil to be flowed between the tubes.
 14. The oil cooler as set forth in claim 13, wherein the communicating portions are formed on an area of all the tubes in the direction perpendicular to a flow direction of oil in the tube to allow oil flowed in the specific tube to be flowed into all other tubes through the communicating portions. 